The specular angle is defined in relation to a spectrophotometer as the angle of reflectance equal and opposite to the angle of incident, illuminant light based on the normal line to the surface coating being measured. The specular angle is also referred to as the gloss angle. By way of example, in conventional handheld spectrophotometers, the specular angle is denoted as “45as0,” or 45 aspecular 0, where the incident light is at 45 degrees to the normal of the target and the reflected light data is gathered at 0 degrees from specular or the equal and opposite 45 degrees from normal, thereby specular itself.
Typically, specular angle data is not gathered or reported in spectrophotometer data because there is an assumption that the data at the angle is highly variable due to the extremely high reflectance data received at the angle. Also, because of the very high reflectance data retrieved from the instrumentation, the shape of the reflectance curve of the specular angle always looks the same for every sample, despite the color or gonioeffects of the sample.
Thus, a need exists for systems and methods that utilize specular angle data to characterize the particles that are present in a target coating mixture.